Carbon nanotube grafted fibres: a route to advanced hierarchical composites

The feasibility of reinforcing conventional fibre/polymer composites by grafting carbon nanotubes (CNTs) onto the fibre surfaces has been investigated. Different methods were developed for directly growing CNTs on silica and carbon (C320 and IM7) fibres. Pure and N-doped CNTs with controllable length were grown on silica fibres using an injection chemical vapour deposition (ICVD) method. The diameter and crystallinity of both types of CNTs increased during growth, which proceeded via the base-growth mechanism. However, the nature surface of carbon fibres is not favourable for the ICVD method. As an alternative, CNT-grafted carbon fibres were produced using the incipient wetness technique or electrochemical deposition to pre-load catalyst for subsequent CNT growth. The effects of growth parameters on the morphology, density, and alignment of CNTs were explored. The CNT-grafting process maintained or improved the fibre tensile modulus, but resulted in strength degradations, to different extents, depending on the fibre type and growth parameters. The impact of CNT-grafting on the interfacial shear strength (IFSS) was studied using different micromechanical interface tests, based on different fibre/polymer systems. The IFSS was unchanged in push-out tests, likely due to an unusual internal failure of the fibres. In all other cases, the IFSS was significantly increased. Single fibre pull-out tests on C320 carbon fibre/epoxy composites showed a 60% increase, whilst fragmentation tests on poly(methyl methacrylate) composites yielded improvements of 26% and 80-150% for IM7 carbon fibres and silica fibres, respectively. The improvements can be attributed to the increased surface area, excellent fibre wettability by the matrix and mechanical interlocking of CNTs with the matrix. In addition, a new combined in situ AFM/Raman technique proved to be a useful tool to study CNT distribution and orientation within hierarchical composites

Orientational Imaging of Subwavelength Au Particles with Higher Order Laser Modes

We present a new method for the imaging of single metallic nanoparticles that provides information about their shape and orientation. Using confocal microscopy in combination with higher order laser modes, scattering images of individual particles are recorded. Gold nanospheres and nonorods render characteristic patterns reflecting the different particle geometries. In the case of nanorods, the scattering patterns also reveal the orientation of the particles. This novel technique provides a promising tool for the visualization of nonbleaching labels in the biosciences

Calorific values and ash contents of different organs of Masson pine (Pinus massoniana) in southern China

Calorific values of plants are important indices for evaluating and reflecting material cycle and energy conversion in forest ecosystems. Based on the data of Masson Pine (Pinus massoniana) in southern China, the calorific values (CVs) and ash contents (ACs) of different plant organs were analyzed systematically using hypothesis test and regression analysis in this paper. The results show: (i) the CVs and ACs of different plant organs are almost significantly different, and the order by AFCV (ash-free calorific value) from the largest to the smallest is foliage (23.55 kJ/g), branches (22.25 kJ/g), stem bark (21.71 kJ/g), root (21.52 kJ/g) and stem wood (21.35 kJ/g); and the order by AC is foliage (2.35%), stem bark (1.44%), root (1.42%), branches (1.08%) and stem wood (0.33%); (ii) the CVs and ACs of stem woods on top, middle and lower sections are significantly different, and the CVs are increasing from top to lower sections of trunk while the ACs are decreasing; (iii) the mean GCV (gross calorific value) and AFCV of aboveground part are larger than those of belowground part (roots), and the differences are also statistically significant; (iv) the CVs and ACs of different organs are related, to some extent, to diameter, height and origin of the tree, but the influence degrees of the factors on CVs and ACs are not the same

Scattering universality classes of side jump in anomalous Hall effect

The anomalous Hall conductivity has an important extrinsic contribution known as side jump contribution, which is independent of both scattering strength and disorder density. Nevertheless, we discover that side jump has strong dependence on the spin structure of the scattering potential. We propose three universality classes of scattering for the side jump contribution, having the characters of being spin-independent, spin-conserving and spin-flip respectively. For each individual class, the side jump contribution takes a different unique value. When two or more classes of scattering are present, the value of side jump is no longer fixed but varies as a function of their relative disorder strength. As system control parameter such as temperature changes, due to the competition between different classes of disorder scattering, the side jump Hall conductivity could flow from one class dominated limit to another class dominated limit. Our result indicates that magnon scattering plays a role distinct from normal impurity scattering and phonon scattering in the anomalous Hall effect because they belong to different scattering classes

Study on radiative decays of DsJ∗(2860)D^*_{sJ}(2860) and Ds1∗(2710)D^*_{s1}(2710) into DsD_s by means of LFQM

The observed resonance peak around 2.86 GeV has been carefully reexamined by the LHCb collaboration and it is found that under the peak there reside two states $D^*_{s1}(2860)$ and $D^*_{s3}(2860)$ which are considered as $1^3D_1(c\bar s)$ and $1^3D_3(c\bar s)$ with slightly different masses and total widths. Thus, the earlier assumption that the resonance $D^*_{s1}(2710)$ was a $1D$ state should not be right. We suggest to measure the partial widths of radiative decays of $D^*_{sJ}(2860)$ and $D^*_{s1}(2710)$ to confirm their quantum numbers. We would consider $D^*_{s1}(2710)$ as $2^3S_1$ or a pure $1^3D_1$ state, or their mixture and respectively calculate the corresponding branching ratios as well as those of $D^*_{sJ}(2860)$. The future precise measurement would provide us information to help identifying the structures of those resonances .Comment: 8 pages, 4 figures, 1 tabl